ENVIRONMENTAL STABILITY AND TRANSMISSION OF RAT VIRUS

The environmental stability and transmission of a field isolate of rat virus was tested under conditions resembling those that may be encoun tered during the housing of laboratory rats. The rat virus kept in phy siologic salt solutions at room temperature remained infective for at least 5 weeks. Similar virus preparations remained infective after dry ing on a plastic surface for 3 to 5 weeks, depending on initial virus concentration, Varying the protein concentration in the medium had no significant effect on stability. Bedding fi om cages housing infected litters induced seroconversions in sentinel rats for at least 5 weeks after storage of rat virus at room temperature. Infection was transmit ted between rats housed in open cages in a Trexler isolator but not be tween rats housed in microisolator cages connected by tunnels partitio ned by wire screens with a mesh size of 1.67 mm, The results indicate that rat virus can remain infective after prolonged exposure to an amb ient environment and suggest that infection is more readily transmitte d by animal-to-animal contact or by fomites than by aerosolization of exhaled virus.